The present invention relates to an arrangement in connecting a position sensing transducer to an internal combustion engine, the transducer being mounted on the outside of a housing, preferably a cylinder block, in which there is mounted a rotatable means, e.g. a crankshaft, which outside the housing carries a drive means for driving auxiliary equipment.
In multi-cylinder Otto-type I.C. engines it is known to control the ignition timing in the respective combustion chambers with the aid of a mechanically driven distributor, This is usually driven by gearing from the engine camshaft, which is in turn driven from the engine crankshaft via a belt drive. It is thus possible to control the engine ignition timing in response to angular positions of the crankshaft, and thus also in response to piston position in the different cylinders.
Driving the distributor in the way described above results in a plurality of transmission transfers which, due to play between the components concerned, impairs the accuracy of controlling the ignition timing relative the angular positions of the crankshaft. The ignition instant in the respective combustion chamber is of great importance in optimizing the combustion process. Incorrect or inaccurate timing causes drawbacks such as increased fuel consumption, reduced power and/or increased exhaust gas emission.
It is known, for the purpose of better controlling ignition timing, to arrange electrical transducers that sense the camshaft angular positions directly, and in response thereto directly control the respective instants of ignition.
Although this means an improvement in relation to an entirely mechanically driven distributor, there remains the drawback that there may be play in the transmission between crankshaft and camshaft which impairs accuracy.
To achieve the best possible accuracy in controlling ignition timing, it is necessary to directly sense the crankshaft angular position. The possibilities of placing an electric transducer on known engine structures is limited, however, and for this reason such transducers have not found any practical application. Placing a transducer in the engine crankcase causes the transducer to be subjected to a temperature that is too high for it to function in the intended manner. Placing the transducer outside the engine, e.g. on a belt pulley at one end of the crankshaft, results in the transducer being subjected to dirt which can endanger its function.